I have a makefile with 2 different targets – one builds for LINUX executable and the other builds for WINDOWS executable.

linux: $(LINUX_OBJS)
    @echo Linking: $@
    @mkdir -p $(BUILD_DIR)
    @mkdir -p $(BUILD_DIR)/$@
    @$(CC) $(LFLAGS) app.c $+ -o $(BUILD_DIR)/$@/app $(INCLUDES) $(LINUX_INCS)

win: $(WIN_OBJS)
    @echo Linking: $@
    @mkdir -p $(BUILD_DIR)
    @mkdir -p $(BUILD_DIR)/$@
    @$(CC) $(LFLAGS) app.c $+ -o $(BUILD_DIR)/$@/app.exe $(INCLUDES) $(WIN_INCS)

## compiling
$(BUILD_DIR)/linux/%.o $(BUILD_DIR)/win/%.o: $(ROOT_PATH)/%.c
    @echo target: $? ($@)
    @mkdir -p $(dir $@)
    @$(CC) $(CFLAGS) $(WFLAGS) -c -o $@ $^ $(INCLUDES) $(WIN_INCS) $(LINUX_INCS)

clean:
    @rm -f -r $(BUILD_DIR)

I want to add an all option, to build both for linux and for windows, so I added:

all: clean linux win

The problem is that when I it starts building for windows, it only compiles the new files that are relevan for windows only (from $WIN_OBJS)) and therefore fails to link it all.

How can I make it build them both? (so I can keep all object files and final linked execution in corresponding build directory, without being deleted between them)?